U.S. patent application number 11/014596 was filed with the patent office on 2005-06-30 for ink-jet recording head and method for manufacturing ink-jet recording head.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Suzuki, Takumi.
Application Number | 20050140735 11/014596 |
Document ID | / |
Family ID | 34703338 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050140735 |
Kind Code |
A1 |
Suzuki, Takumi |
June 30, 2005 |
Ink-jet recording head and method for manufacturing ink-jet
recording head
Abstract
An ink-jet recording head and a method for manufacturing the
same. The method includes a photosensitive resin layer formed on a
support component and is exposed to light by the use of a mask, so
that through holes are formed. Since the diameters of the through
hole on both sides of the photosensitive resin layer are made
equal, the bonding area of a filter to a substrate is ensured, and
the aperture area of the through hole per unit area is increased. A
maximum aperture diameter is made to be smaller than or equal to a
maximum linear distance between intersection points of a straight
line passing through the geometric center of the ejection nozzle
and an edge of the ejection nozzle. The head substrate and the
filter are press-contacted. The support component is removed. The
resulting recording head can prevent a reduction of the yield due
to non-ejection of ink.
Inventors: |
Suzuki, Takumi; (Kanagawa,
JP) |
Correspondence
Address: |
Canon U.S.A. Inc., Intellectual Property
Department
15975 Alton Parkway
Irvin
CA
92618-3731
US
|
Assignee: |
Canon Kabushiki Kaisha
Tokyo
JP
|
Family ID: |
34703338 |
Appl. No.: |
11/014596 |
Filed: |
December 16, 2004 |
Current U.S.
Class: |
347/56 |
Current CPC
Class: |
B41J 2/1404 20130101;
B41J 2/14145 20130101; B41J 2002/14387 20130101; Y10T 29/49401
20150115; B41J 2002/14403 20130101; B41J 2/17563 20130101; Y10T
29/49083 20150115 |
Class at
Publication: |
347/056 |
International
Class: |
B41J 002/05 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2003 |
JP |
2003-434527 |
Nov 11, 2004 |
JP |
2004-327664 |
Claims
What is claimed is:
1. An ink-jet recording head comprising: a substrate having a first
surface and a second surface opposing the first surface; ejection
nozzles provided about the first surface; thermal energy generating
elements disposed about the ejection nozzles at the first surface;
an ink supply hole penetrating through the first surface to the
second surface; and a filter disposed on the second surface of the
substrate such that the filter covers the ink supply hole at the
second surface, wherein the filter includes a plurality of through
holes, wherein each though hole has an aperture diameter smaller
than or equal to a maximum linear distance between intersection
points of a straight line passing through a geometric center of the
ejection nozzle and an edge of the ejection nozzle.
2. The ink-jet recording head according to claim 1, wherein the
first surface of the substrate includes a flow-path-forming
component including the ejection nozzles and channels connecting
the ejection nozzles and the ink supply hole.
3. The ink-jet recording head according to claim 1, wherein the
substrate includes a plurality of ink supply holes.
4. The ink-jet recording head according to claim 1, wherein each of
the plurality of through holes has a substantially circular shape
having a diameter smaller than or equal to the linear distance.
5. The ink-jet recording head according to claim 1, wherein the
filter includes a photosensitive resin bonded to the second surface
of the substrate.
6. The ink-jet recording head according to claim 1, further
comprising a first metal layer disposed on the filter, and a second
metal layer disposed on the second surface of the substrate,
wherein the first and second metal layers are joined.
7. The ink-jet recording head according to claim 1, wherein an
aperture area of the ink supply hole at the second surface of the
substrate is larger than an aperture area of the ink supply hole at
the first surface.
8. The ink-jet recording head according to claim 2, wherein an
aperture area of the ink supply hole at the second surface of the
substrate is larger than an aperture area of the ink supply hole at
the first surface.
9. The ink-jet recording head according to claim 3, wherein an
aperture area of the ink supply hole at the second surface of the
substrate is larger than an aperture area of the ink supply hole at
the first surface.
10. The ink-jet recording head according to claim 4, wherein an
aperture area of the ink supply hole at the second surface of the
substrate is larger than an aperture area of the ink supply hole at
the first surface.
11. A method for manufacturing an ink-jet recording head provided
with ejection nozzles, the method comprising the steps of: forming
a support component; forming a resin layer on the support
component; forming a plurality of through holes in the resin layer
such that each through hole has an aperture diameter smaller than
or equal to a maximum linear distance between intersection points
of a straight line passing through the geometric center of the
ejection nozzle and an edge of the ejection nozzle; forming a
substrate including a first surface and a second surface opposing
the first surface, the ejection nozzles provided about the first
surface, thermal energy generating elements disposed about the
ejection nozzles at the first surface, and an ink supply hole
penetrating through the first surface to the second surface;
joining the resin layer to the second surface of the substrate; and
removing the support component from the resin layer.
12. The method for manufacturing an ink-jet recording head
according to claim 11, wherein the support component includes at
least one of a silicon wafer and a metal capable of being
etched.
13. The method for manufacturing an ink-jet recording head
according to claim 11, wherein the resin layer includes a
photosensitive resin.
14. The method for manufacturing an ink-jet recording head
according to claim 11, wherein the joining step includes the steps
of: coating the second surface of the head substrate with a
polyamide; joining the resin layer provided with through holes into
intimate contact with the second surface coated with the polyamide;
and performing heat bonding.
15. The method for manufacturing an ink-jet recording head
according to claim 11, the method further comprising the steps of:
forming a metal layer on the resin layer after the step of forming
the resin layer on the support component; forming the through holes
in the metal layer and the resin layer; forming a head-side metal
layer on the second surface of the substrate; cleaning the metal
layer and the head-side metal layer with a cleaning gas in a vacuum
atmosphere; and joining the metal layer into intimate contact with
the head-side metal layer and then pressurizing the metal layer
joined with the head-side metal layer.
16. The method for manufacturing an ink-jet recording head
according to claim 15, further comprising a step of heating the
metal layer joined with the head-side metal layer after the step of
joining the metal layer into intimate contact with the head-side
metal layer.
17. The method for manufacturing an ink-jet recording head
according to claim 11, wherein the step of forming the through
holes includes forming the through holes in an area of the resin
layer larger than an aperture area of the ink supply hole.
18. The method for manufacturing an ink-jet recording head
according to claim 11, wherein the step of forming the substrate
includes the step of forming the ink supply hole such that an
aperture area of the ink supply hole at the second surface is
larger than an aperture area of the ink supply hole at the first
surface.
19. An ink jet recording head manufactured by the method according
to claim 11.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an ink-jet recording head
provided with a filter and a method for manufacturing the same. In
particular, the present invention relates to an ink-jet recording
head provided with an ink supply hole penetrating from a bottom
surface to a top surface of a substrate including a plurality of
ejection nozzles and a method for manufacturing the ink-jet
recording head.
[0003] 2. Description of the Related Art
[0004] Known ink-jet recording heads can form fine ink droplets by
downsizing ejection nozzles to eject ink, and have become
mainstream photorealistic printers in recent years. However, as
ejection nozzles become finer, a problem of clogging of the
ejection nozzle occurs due to dust contained in ink.
[0005] Consequently, ink-jet recording heads incorporating filters
to remove the dust have been developed.
[0006] FIG. 1 is a sectional side view showing an example of a
known ink-jet recording head provided with a filter.
[0007] An ink-jet recording head 420 includes electrothermal
conversion elements, although not shown in the drawing, which
generate thermal energy to initiate film boiling of ink in
accordance with electric signals, in an ink flow path 415; ejection
nozzles 411 to eject ink, located at positions in accordance with
electrothermal conversion elements; an ink supply hole 412 to
supply ink from an ink tank to the ink flow path 415; and a
columnar filter 404 disposed in the ink flow path 415. As shown in
FIGS. 2A-C, this filter 404 is disposed in such as manner that a
spacing A in the filter 404 is smaller than or equal to a maximum
linear distance between intersection points of a straight line
passing through the geometric center of the ejection nozzle 411 and
an edge of the ejection nozzle 411 in a plan view when viewed from
an ejection nozzle surface (top surface) side. That is, in the
configuration shown in FIGS. 2A-C, since the ejection nozzle is
circular, the geometric center of the ejection nozzle 411 is the
center of the circle. Therefore, a straight line passing through
this center and having a maximum distance between points of
intersection with the circumference of the circle of the ejection
nozzle 411 refers to a diameter (refers to a major axis when the
ejection nozzle 411 is elliptical, for example). Accordingly, the
filter 404 is disposed such that the spacing A is smaller than or
equal to the diameter A' of the ejection nozzle 411.
[0008] With respect to the filter 404 in which columns are set up
in the ink flow path 415, when the two-dimensional relationship
between positions is viewed from the top surface, the spacing A
shown in FIGS. 2A-C is smaller than or equal to the diameter of the
ejection nozzle 411. However, in the recording head which ejects
fine droplets, even when the diameter of an ejection nozzle is
reduced, it is difficult to correspondingly decrease the ink flow
path height B because the performance of refilling ink must be
maintained. Consequently, when such a recording head is viewed from
the direction indicated by an arrow D shown in FIG. 2B, since the
height B of the ink flow path 415 is larger than the spacing A in
the filter 404, as shown in FIG. 2C, if slim dust flows into the
ink flow path 415 while being vertically oriented, the dust passes
through the filter 404. However, the dust cannot be ejected through
the ejection nozzle 411, so that non-ejection of the ink may
result.
[0009] On the other hand, schemes to prevent the entrance of dust
may be devised. A component provided with fine holes may be
attached to an ink supply hole for supplying ink to a plurality of
ink flow paths, or a part of an ink flow path may be processed to
have through holes.
[0010] For example, Japanese Patent Laid-Open No. 5-254120
discloses a method, in which fine through holes are formed by
downstream processing in appropriate portions of an ink flow path
and a liquid chamber. In this method, a component having an
adequate strength to form the ink flow path and the liquid chamber
is required. In general, laser processing is used for boring
through holes therein. However, when the downstream processing is
performed by laser processing or other means, dust may enter into
the ink flow path and the liquid chamber during the formation of
through holes in the component. As a result, since the dust cannot
be taken out because of the characteristic of the through holes
(filter), a cause of non-ejection of ink may be generated defying
expectations.
[0011] Japanese Patent Laid-Open No. 5-208503 (corresponding U.S.
Pat. No. 5,141,596) discloses a method, in which silicon is
subjected to ion implantation and, thereby, a portion sensitive to
etching and a portion resistant to etching are formed, so that an
ink supply hole and an ink chamber are formed and, at the same
time, through holes are bored, the through holes having a dimension
smaller than or equal to a minimum distance between two
intersection points of a straight line passing through the
geometric center of the ejection nozzle and a circumference of the
above-described ejection nozzle.
[0012] However, in this method, since the area of the through holes
are determined based on the diffusion of ions, the concentration
due to diffusion does not become two values corresponding to a
portion sensitive to etching and a portion resistant to etching,
but there are gradations in concentration. Therefore, the size of
the through holes cannot be precisely controlled. Since anisotropic
etching is performed from a surface opposite to the surface to be
provided with through holes, if the area of the portion provided
with through holes (filter) is increased, the area to become a
liquid chamber is increased and, therefore, the formation becomes
difficult. Therefore, the area of the portion to be provided with
the through holes is restricted. The portion to be provided with
the through holes becomes very narrow since the formation is
performed by anisotropic etching of silicon. Consequently, when
solid printing or the like in which ink is ejected from a plurality
of ejection nozzles is performed, a pressure drop is increased and,
therefore, high-speed printing becomes difficult. Furthermore,
since the liquid chamber is disposed, alignment is required for
joining to a wafer including ejection nozzles.
[0013] Japanese Patent Laid-Open No. 2000-094700 discloses that the
above-described fine through holes are formed in a portion having a
large area. However, since the formation of an ink supply hole is
performed simultaneously, an etching solution for forming the ink
supply hole must be penetrated through the fine through holes, and
when a mold material for the ink flow path is removed, the mold
material for the ink flow path must be fused and removed under the
condition in which both the ejection nozzle and the through holes
are small holes. Therefore, the operability of the removal is poor,
and this method is impractical.
SUMMARY OF THE INVENTION
[0014] The present invention is directed to an ink-jet recording
head not only capable of preventing a reduction of the yield due to
non-ejection of ink and reducing a cost, but also compatible with
high-speed printing, and therefore, adaptable to a high-quality
printer which ejects small droplets. The present invention is also
directed to a method for manufacturing an ink-jet recording
head.
[0015] In one aspect of the present invention, an ink-jet recording
head includes: a substrate having a first surface and a second
surface opposing the first surface; ejection nozzles provided about
the first surface; thermal energy generating elements disposed
about the ejection nozzles at the first surface; an ink supply hole
penetrating through the above-described first surface to the
above-described second surface; and a filter disposed on the second
surface of the above-described substrate such that the filter
covers the ink supply hole at the second surface, wherein the
filter includes a plurality of through holes, wherein each through
hole has an aperture diameter smaller than or equal to a maximum
linear distance between intersection points of a straight line
passing through the geometric center of the above-described
ejection nozzle and an edge of the above-described ejection
nozzle.
[0016] In the ink-jet recording head having the above-described
configuration, according to the present invention, a filter is
provided with through holes formed in order that dust which cannot
be ejected through the ejection nozzle due to a large size (that
is, a size which can causes clogging of the ejection nozzle) does
not pass through the filter. Therefore, non-ejection of the
ejection nozzle can be prevented from occurring due to dust passed
through the filter.
[0017] In another aspect, a method for manufacturing an ink-jet
recording head includes the steps of: forming a support component;
forming a resin layer on the support component; forming a plurality
of through holes in the above-described resin layer such that each
through hole has an aperture diameter smaller than or equal to a
maximum linear distance between intersection points of a straight
line passing through the geometric center of the above-described
ejection nozzle and an edge of the above-described ejection nozzle;
forming a substrate including a first surface and a second surface
opposing the first surface, the ejection nozzles provided about the
first surface, thermal energy generating elements disposed about
the ejection nozzles at the first surface, and an ink supply hole
penetrating through the first surface to the second surface;
joining the resin layer to the second surface of the substrate; and
removing the support component from the above-described resin
layer.
[0018] In the above-described method for manufacturing an ink-jet
recording head, according to the present invention, a filter is
provided with through holes formed in order that dust which cannot
be ejected through the ejection nozzle due to a large size does not
pass through the filter. This filter is joined to a bottom surface
side of the substrate where the ink supply hole has a large
aperture area. Consequently, an ink-jet recording head produced by
the manufacturing method of the present invention can prevent
non-ejection of the ejection nozzle from occurring due to dust
passing through the filter. In addition, the number of through
holes becomes larger than that in the case where a filter is
disposed on the top surface side of the substrate and, therefore,
the resistance to flow can be reduced when the ink flows into the
ink flow path. That is, the manufacturing method of the present
invention can produce an ink-jet recording head not only capable of
preventing a reduction of the yield due to non-ejection of ink and
reducing a cost, but also compatible with high-speed printing, and
therefore, adaptable to a high-quality printer which ejects small
droplets.
[0019] As described above, according to the ink-jet recording head
of the present invention, the reduction of the yield due to
non-ejection of ink can be prevented, the cost can be reduced. In
addition, the recording head is compatible with high-speed printing
and, therefore, is adaptable to a high-quality printer which ejects
small droplets.
[0020] Further features and advantages of the present invention
will become apparent from the following description of the
embodiments (with reference to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a sectional side view showing an example of the
structure of a known ink-jet recording head provided with a
filter.
[0022] FIGS. 2A to 2C are partial sectional views showing a
detailed structure of the filter of the ink-jet recording head
shown in FIGS. 5A to 5E.
[0023] FIGS. 3A to 3D are step diagrams showing a filter formation
process in the method for manufacturing an ink-jet recording head
according to a first embodiment of the present invention.
[0024] FIGS. 4A to 4C are schematic diagrams for explaining the
difference in aperture diameters of through holes depending on the
methods for forming a filter.
[0025] FIGS. 5A to 5E are step diagrams showing a filter formation
process in the method for manufacturing an ink-jet recording head
according to a second embodiment of the present invention.
[0026] FIGS. 6A to 6E are step diagrams showing a filter formation
process in the method for manufacturing an ink-jet recording head
according to a third embodiment of the present invention.
[0027] FIGS. 7A and 7B are illustrative diagrams showing the method
for manufacturing an ink-jet recording head of the present
invention. FIG. 7A is a perspective view for explaining the
condition in which a support component and a filter are joined to a
substrate. FIG. 7B is a schematic diagram for explaining positions
of the filter and an ink supply hole when the ink-jet recording
head in which the filter is joined by the method shown in FIG. 7A
is viewed from the back.
[0028] FIGS. 8A and 8B are illustrative diagrams showing a modified
example of the ink-jet recording head of the present invention.
FIG. 8A is a sectional side view. FIG. 8B is a schematic diagram
for explaining positions of a filter and ink supply holes when the
recording head is viewed from the back.
DESCRIPTION OF THE EMBODIMENTS
[0029] First Embodiment
[0030] FIGS. 3A to 3D are step diagrams showing a filter formation
process in the method for manufacturing an ink-jet recording head
according to the present embodiment.
[0031] Silicon, aluminum that is a metal capable of being etched,
or the like serving as a support component 2 to support a
photosensitive resin layer 1 described below is formed to have a
size similar to the size of a silicon wafer to form a head
substrate 10 (FIG. 3C). This support component 2 is spin-coated
with an epoxy resin of about 20 .mu.m in thickness containing a
photopolymerization initiator. Pre-baking is performed in order to
evaporate a solvent in the resin, so that the photosensitive resin
layer 1 is formed (FIG. 3A).
[0032] The method for manufacturing the photosensitive resin layer
1 is not limited to the above-described spin coating method, and
may be a spraying method, a printing method, or the like. A desired
thickness of coating can be applied by various methods, for
example: a slit coating method can be performed in which discharge
is performed linearly from a slit having a constant width and,
thereby, a wafer is coated at a uniform speed and a uniform
interval; a method in which spinning is performed after the slit
coating; and a method in which a rotating wafer is coated from a
center or a perimeter portion while a dropping nozzle is moved in a
manner similar to that in the case where a picture is drawn with a
single stroke of the brush.
[0033] This photosensitive resin layer 1 is of a negative type, and
a portion exposed to light is cross-linked to become insoluble in a
developing solution, so that patterning can be performed. A
vertical hole having a diameter of about 5 .mu.m can be formed with
respect to a thickness of 20 .mu.m. In the present embodiment, the
thickness of the photosensitive resin layer 1 is set at about 20
.mu.m for safety. However, the thickness can be further decreased
when a pressure drop of ink is large. In addition to liquid resins,
a photosensitive epoxy resin (SU-8 2005 produced by MicroChem
Corp., or the like) may be made into a dry film and laminated on
the support component 2.
[0034] The photosensitive resin layer 1 is exposed to light with an
exposure apparatus by the use of a mask of through holes 3 (not
shown in the drawing). In the present embodiment, circular through
holes having a diameter of about 6 .mu.m are formed. The resin used
in the present embodiment is of a negative type, and a portion not
exposed to light is dissolved in a developing solution, and a
portion exposed to light is cross-linked to become insoluble in the
developing solution. A mixed solution of methyl isobutyl ketone
(MIBK) and xylene is used as the developing solution.
Alternatively, no photosensitive resin is used in contrast to the
present embodiment, a thermosetting epoxy resin may be disposed
and, thereafter, the resin may be coated with a resist having high
resistance to etching. Subsequently, a pattern of the through holes
3 may be formed with an exposure apparatus in a manner similar to
that in the above-described method, and the through holes 3 may be
formed by dry etching.
[0035] With respect to the area of a region to be provided with
through holes 3, the through holes 3 are disposed all over the
photosensitive resin layer 1, or the through holes 3 are disposed
in an area larger than the aperture area in a bottom surface 10a
side of an ink supply hole 12. In this manner, even when the region
provided with the through holes 3 and the ink supply hole 12 are
somewhat misaligned in the arrangement, since the portion provided
with the through holes 3 of a filter 4 is located at the portion of
the ink supply hole 12 with no problem, intentional alignment
becomes unnecessary.
[0036] Here, FIGS. 4A to 4C will be described. When the through
holes 3 are formed by exposing the photosensitive resin layer 1 to
light with an exposure apparatus by the use of a mask of the
through holes 3, the diameters of the through hole on both surface
sides of the photosensitive resin layer 1 are allowed to become the
same diameter dl (FIGS. 4A and 4B).
[0037] On the other hand, when through holes 3' having a diameter
of d2 are formed by anisotropic etching of silicon, as shown in
FIG. 4C, the diameter d2' in the anisotropic etching start side
becomes larger than the diameter d2. Consequently, the aperture
area per unit area of the through holes 3' inevitably becomes
smaller than that in the present embodiment. When the through holes
3' are formed by anisotropic etching and, in addition, the aperture
area per unit area of the through holes 3' is increased, a bonding
area to the substrate cannot be adequately ensured. As described
above, according to the manufacturing method of the present
embodiment, a bonding area of the filter 4 to the substrate 13 can
be ensured adequately and, in addition, the aperture area per unit
area of the through holes 3 can be increased.
[0038] The diameter d1 of the through hole 3 is made smaller than
or equal to a maximum linear distance between intersection points
of a straight line passing through the geometric center of the
ejection nozzle 11 and an edge of the ejection nozzle 11 in the
plan view when viewed from the ejection nozzle surface (top
surface) side. That is, when the ejection nozzle 11 is circular,
the diameter d1is made smaller than or equal to the diameter d0 of
the ejection nozzle 11 (FIGS. 4A and 4B). When the shape of the
ejection nozzle 11 is, for example, elliptical, a maximum distance
between intersection points of a straight line passing through the
geometric center of the ejection nozzle 11 and an edge of the
ejection nozzle 11 refers to a major axis and, in this case, the
diameter d1 of the through hole 3 is shorter than the major axis of
the elliptical ejection nozzle 11. When the shape of the ejection
nozzle 11 is rectangular, a maximum distance between intersection
points of a straight line passing through the geometric center of
the ejection nozzle 11 and an edge of the ejection nozzle 11 refers
to a diagonal and, in this case, the diameter d1 of the through
hole 3 is shorter than the diagonal of the rectangular ejection
nozzle 11.
[0039] After the through holes 3 are formed as described above, in
order to improve the chemical agent resistance, baking is performed
at 100.degree. C. for 1 hour, so that a filter 4 is formed on the
support component 2 (FIG. 3B).
[0040] Subsequently, about 5 .mu.m of polyamide is transferred to
the bottom surface 10a of the head substrate 10.
[0041] The head substrate 10 is formed beforehand by the usual
procedure. However, the procedure is suspended before
high-temperature baking to enhance the adhesion of a
flow-path-forming component to a substrate 13, while the
flow-path-forming component forms a plurality of ejection nozzles
11 and channels serving as a plurality of ink flow paths 6 in
accordance with respective ejection nozzles 11. That is, the head
substrate 10 is formed beforehand as described below. Thermal
energy generating elements, although not shown in the drawing, to
generate thermal energy for ejecting ink are disposed at positions
in accordance with the plurality of ejection nozzles 11, on a top
surface 10b of the substrate 13. Mold materials (not shown in the
drawing) in accordance with the channels serving as the plurality
of ink flow paths 6 are formed on the substrate 13. Furthermore, a
nozzle material serving as a flow-path-forming component 5 is
formed to cover the mold materials. The ink supply hole 12 is
formed by anisotropic etching from the bottom surface 10a side. In
this manner, the ink supply hole 12 having an aperture area in the
bottom surface 10a side larger than that in the top surface 10b
side is formed. Subsequently, the mold materials in accordance with
the channels serving as the ink flow paths 6 are removed and,
thereby, the ejection nozzles 11 and the ink flow paths 6 are
formed by the flow-path-forming component 5, so that the head
substrate 10 is formed. However, the procedure is suspended before
the final high-temperature baking to enhance the adhesion of the
flow-path-forming component 5.
[0042] The polyamide is transferred to the bottom surface 10a of
the head substrate 10 prepared beforehand as described above. In
the transferring method, Teflon is coated with the polyamide of 5
.mu.m in thickness, and the head substrate 10 is placed thereon.
Consequently, the polyamide does not enter the ink supply hole 12,
and the polyamide can be transferred only on a bonding portion 14.
When etching is performed vertically, the aperture areas of the ink
supply hole 12 in the ejection nozzle 11 side and the bottom
surface 10a side become equal to each other. When the ink supply
hole 12 is formed by anisotropic etching of the substrate 13 made
of silicon, the aperture area in the bottom surface 10a side
becomes the largest. Therefore, it is desirable that the ink supply
hole 12 is formed by anisotropic etching of the silicon substrate
13. The polyamide used as an adhesive in the present embodiment can
be, for example, HL-1200 produced by Hitachi Chemical Company,
Ltd.
[0043] A bonding surface, which is the photosensitive resin layer 1
side of the support component 2 supporting the photosensitive resin
layer 1 provided with the through holes 3, is placed on the bonding
portion 14 of the bottom surface 10a of this head substrate 10, and
these are press-contacted in order that no gap is created
therebetween. Under this condition, heating is performed in an oven
at 200.degree. C. for 1 hour, so that the polyamide is cured, and
the photosensitive resin layer 1 provided with the through holes 3
and the head substrate 10 are brought into intimate contact (FIG.
3C).
[0044] The support component 2 is removed. In the present
embodiment, a jig (not shown in the drawing) is used to avoid
contact of an etching solution with the surface provided with
ejection nozzles 11 of the head substrate 10, and the support
component 2 is removed by being dissolved in an organic alkali,
tetramethylammonium hydroxide (TMAH), heated to 85.degree. C. In
the present embodiment, the support component 2 has a thickness of
about 0.2 mm, and is completely removed after about 6 hours. In
addition to this, examples of methods for removing the support
component 2 may include a technique for slimming a substrate, e.g.,
back grind, chemical mechanical planarization (CMP), or spin
etching.
[0045] Washing with water is performed after the support component
2 is removed, so that an ink-jet recording head 20 provided with
the filter 4 on the aperture 12a of the ink supply hole 12 is
formed (FIG. 3D).
[0046] Thereafter, as in the known manner, the wafer is separated
to have a required shape, an external electrode is connected and,
for example, a component to connect to an ink tank is attached.
[0047] In this manner, the ink-jet recording head 20 according to
the present embodiment, provided with the filter 4 is completed,
wherein the filter 4 is formed in order that the diameter of the
through hole 3 is made smaller than or equal to a maximum linear
distance between intersection points of a straight line passing
through the geometric center of the ejection nozzle 11 and an edge
of the ejection nozzle 11.
[0048] In the filter 4 of the ink-jet recording head 20 in the
present embodiment, the through hole 3 has the above-described
aperture dimension. Consequently, dust passing through the through
holes 3 of the filter 4 has a size which allows the dust to be
ejected from the ejection nozzle 11 and, therefore, the problem of
non-ejection of ink due to dust passing through the filter is
overcome.
[0049] Since the filter 4 is joined to the bottom surface 10a side
of the substrate 13, where the ink supply hole 12 has a large
aperture area, the number of through holes becomes larger than that
in the case where the filter is disposed in the top surface side of
the substrate. Therefore, the resistance to flow can be reduced
when the ink flows into the ink flow path. That is, the ink-jet
recording head 20 in the present embodiment is not only capable of
preventing a reduction in yield due to non-ejection of ink and
reducing a cost, but also is compatible with high-speed printing
and, therefore, an ink-jet recording head adaptable to a
high-quality printer which ejects small droplets can be
produced.
[0050] The filter 4 of the ink-jet recording head 20 in the present
embodiment has a thickness t.sub.2 of about 20 .mu.m, while the
flow-path-forming component 5 has a thickness t.sub.1 of about 20
to 30 .mu.m. Since the thickness of the filter is made to be the
same level (the same order) as the thickness of the
flow-path-forming component, and resin layers having the same level
of thickness are disposed on both surfaces of the substrate, warp
of the substrate generated when the flow-path-forming component is
brought into intimate contact with the substrate in FIG. 3C can be
reduced. In order to realize the above-described reduction of warp,
it is desirable to dispose the filter 4 all over the bottom surface
of the substrate.
[0051] Second Embodiment
[0052] FIGS. 5A to 5E are step diagrams showing a filter formation
process in a method for manufacturing an ink-jet recording head
according to a second embodiment.
[0053] In the present embodiment, an etching-protective film is
formed in the step of forming the filter, and other steps are
similar to those in the first embodiment. Therefore, only the steps
different from those in the first embodiment will be described
below in detail.
[0054] About 3,000 angstroms of silicon dioxide (SiO.sub.2) serving
as an etching-protective film 105 is formed on a support component
102, on the side to be provided with a photosensitive resin layer
101. Subsequently, the photosensitive resin layer 101 is formed on
the etching-protective film 105 in a manner similar to that in the
first embodiment (FIG. 5A).
[0055] Through holes 103 are formed in the photosensitive resin
layer 101 as in the first embodiment (FIG. 5B), and the
photosensitive resin layer 101 provided with the through holes 103
is joined to a bonding portion 114 of a bottom surface 110a of a
head substrate 110 (FIG. 5C).
[0056] The support component 102 is removed by being dissolved in
an organic alkali, tetramethylammonium hydroxide (TMAH), heated to
85.degree. C. In the present embodiment, the support component 102
has a thickness of about 0.2 mm, and is completely removed after
about 6 hours. Even if the time exceeds about 6 hours, the
etching-protective film made of silicon dioxide serves as an
etching-stop layer. Therefore, the etching solution does not enter
an ink supply hole 112, and the inside is kept clean (FIG. 5D).
[0057] Subsequently, the etching-protective film 105 is removed
with ammonium fluoride, and washing with water is performed, so
that an ink-jet recording head 120 provided with a filter 104 on an
aperture 112a of the ink supply hole 112 is formed (FIG. 5E).
Thereafter, as in the known manner, the wafer is separated to have
a required shape, an external electrode is connected and, for
example, a component to connect to an ink tank is attached.
[0058] In this manner, the ink-jet recording head according to the
present embodiment, provided with the filter 104 is completed,
wherein the filter 104 is formed such that the diameter of the
through hole 103 is made smaller than or equal to a maximum linear
distance between intersection points of a straight line passing
through the geometric center of the ejection nozzle 111 and an edge
of the ejection nozzle 111.
[0059] Third Embodiment
[0060] FIGS. 6A to 6E are step diagrams showing a filter formation
process in a method for manufacturing an ink-jet recording head
according to a third embodiment.
[0061] In the present embodiment, joining between a head substrate
and a filter is performed by a metallic bond, and other steps are
similar to those in the first and second embodiments. Therefore,
only the steps different from those in the second embodiment will
be described below in detail.
[0062] About 3,000 angstroms of silicon dioxide (SiO.sub.2) serving
as an etching-protective film 205 is formed on a support component
202, on the side to be provided with a photosensitive resin layer
201. Subsequently, the photosensitive resin layer 201 is formed on
the etching-protective film 205 in a manner similar to that in the
first and second embodiments, and a metal layer 206 is further
formed (FIG. 6A). In the present embodiment, the metal layer 206 is
formed from gold of about 5,000 angstroms in thickness. Examples of
methods for forming the metal layer include vacuum evaporation,
sputtering, electrolysis, and electroless plating. In the present
embodiment, the metal layer 206 is formed by sputtering.
[0063] Through holes 203 are formed in the photosensitive resin
layer 201 as in the first and second embodiments, so that a filter
204 is formed on a support component 202 (FIG. 6B).
[0064] On the other hand, as described in the first embodiment, the
head substrate 210 is formed beforehand in the usual procedure, and
the procedure is suspended before high-temperature baking to
enhance the adhesion of a flow-path-forming component to the
substrate 13, while the flow-path-forming component forms a
plurality of ejection nozzles 211 and channels serving as a
plurality of ink flow paths 6 in accordance with respective
ejection nozzles 211. At this time, a substrate-side metal layer
215 is formed on a bottom surface 210a in the step of forming an
ink supply hole 212 of the head substrate 210, and is left on a
bonding portion 214. Preferably, gold, aluminum, copper, or the
like is used as the substrate-side metal layer 215, and a method
for manufacturing the substrate-side metal layer 215 may be any one
of vacuum evaporation, sputtering, electrolysis, electroless
plating, and the like.
[0065] In this manner, the filter 204 including the metal layer 206
as an uppermost layer and the head substrate 210 including the
substrate-side metal layer 215 on the bonding portion 214 of the
bottom surface 210a are formed.
[0066] The metal layer 206 of the filter 204 and the substrate-side
metal layer 215 of the head substrate 210 are faced to each other,
and are put in a vacuum chamber, although not shown in the drawing.
Argon is used as a cleaning gas, and the metal surfaces are
subjected to reverse sputtering with argon plasma, so that each
metal surface is made to be a cleaned surface. The substrates are
brought into contact with each other without being further treated,
and a force of about 4.9 N is applied, so that the metal layer 206
and the substrate-side metal layer 215 are joined (FIG. 6C). The
metal layer 206 and the substrate-side metal layer 215 may be
joined at ambient temperature, or be joined by heating. The metal
layer 206 and the substrate-side metal layer 215 may be joined by
being brought into contact without application of a pressure, and
at this time, the joining may be performed at ambient temperature
or by heating.
[0067] Subsequently, the support component 202 is removed by
dissolution as in each of the above-described embodiments (FIG.
6D), the etching-protective film 205 is removed with ammonium
fluoride, and washing with water is performed, so that an ink-jet
recording head 220 provided with the filter 204 on an aperture 212a
of the ink supply hole 212 is formed (FIG. 6E). Thereafter, as in
the known manner, the wafer is separated to have a required shape,
an external electrode is connected and, for example, a component to
connect to an ink tank is attached.
[0068] In this manner, the ink-jet recording head according to the
present embodiment, provided with the filter 204 is completed,
wherein the filter 204 is formed in order that the diameter of the
through hole 203 is made smaller than or equal to a maximum linear
distance between intersection points of a straight line passing
through the geometric center of the ejection nozzle 211 and an edge
of the ejection nozzle 211.
[0069] Supplemental descriptions will be provided on the
manufacturing methods in the above-described embodiments, and a
modified example applicable to each of the embodiments will be
described with reference to FIGS. 7A and 7B and FIGS. 8A and
8B.
[0070] In each of the methods for manufacturing an ink-jet
recording head of the present invention, the filter disposed on the
support component is bonded or joined to the substrate provided
with the ink supply hole. In the description of each embodiment,
the number of recording head was limited to one in order to
simplify the explanation. However, in practice, a plurality of
recording heads (chips) are prepared on one wafer through, for
example, a process for manufacturing a semiconductor. Thereafter,
the wafer is cut, and the resulting recording head is connected to
an external electrode and an ink tank.
[0071] Here, as shown in FIG. 7A, when the filter is attached to
the head substrate 10 provided with the flow-path-forming
components, wafers are joined to each other in the present
invention. At this time, since the above-described filter 4 has
been formed all over the support component, it is unnecessary to
make sure the filter is in a proper alignment with an ink supply
hole 12 of each chip during joining. FIG. 7B is a schematic diagram
of the recording head viewed from the back of the substrate,
wherein the recording head was cut from the wafer after a plurality
of through holes were disposed at a constant spacing. As is clear
from this schematic diagram, through holes are disposed at a
constant spacing all over the back of the substrate of the head,
and a portion, where the ink supply hole 12 is present, practically
performs the function as a filter.
[0072] FIGS. 8A and 8B show a modified example applicable to each
embodiment of the present invention. In above-described each
embodiment, one recording head is provided with one ink supply
hole. However, as shown in FIGS. 8A and 8B, the present invention
can be applied to a recording head provided with a plurality of ink
supply holes 12. The ink supply holes may be supplied with mutually
different types of ink, or be supplied with the same ink. With
respect to such a recording head as well, by applying the present
invention, it is unnecessary to give attention to the alignment
when the filter is disposed on each ink supply hole, as shown in
FIG. 8B. Consequently, a recording head having a desired
performance of removing dust can readily be provided.
[0073] While the present invention has been described with
reference to what are presently considered to be the embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments. On the contrary, the invention is intended
to cover various modifications and equivalent arrangements included
within the spirit and scope of the appended claims. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
[0074] This application claims priority from Japanese Patent
Application Nos. 2003-434527 and 2004-327664 filed Dec. 26, 2003
and Nov. 11, 2004, respectively, which are hereby incorporated by
reference herein.
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